A person who is combative can be strapped to a chair to prevent further assaults on detention personnel, and to try to prevent the person from hurting himself. Medical or detention personnel should remove the spit hood if they leave the room and the person is unattended.
I can't emphasize the word "generalize" enough though. The underlying issue in this case is the problem of mental illness. As it is, there is no definitive law enforcement solution to a person who keeps committing crimes, other than incarceration. And if the person has a mental health problem, the closest to solving the problem with that particular individual is the get him some mental health care. And even then, there is no guarantee that at some point he will not commit additional crimes, or harm himself or others.
In the case we are posting about, law enforcement personnel had the ample opportunity to make reasonable decisions, and it appears that some of them failed miserably.
Which can look the same as a meth user!